The Role of Job Satisfaction as Mediator Between Human Resource Practices and Employees' Performance Among the Cargos' Employees at Saudi Ports Authority Based on the Motivation Theories

Saudi ports, which are one of the busiest seaports in the world and the biggest ports in the Middle East region, have recently encountered a critical problem of overstock or accumulation of goods. It is imperative that these ports have the capacity to release cargoes and goods timely. However, the inadequacy in human resource practices has resulted in dissatisfaction and low performance among cargo employees. Moreover, the relationships of human resource practices, job satisfaction, and job performance within the context of Middle East region, remain underexplored. Addressing that, this study will evaluate the mediating effect of job satisfaction in the relationship between human resource practices (i.e., training and development, reward, job analysis, recruitment and selection, social support, employee relations, and employees’ empowerment) and job performance among cargo employees in Saudi Ports Authority with respect to Adams’ Equity Theory and Maslow’s Hierarchy of Needs using the questionnaire survey approach.


Introduction
The Kingdom of Saudi Arabia (KSA) is the world's main oil exporter and possesses the largest, most diversified economy in the Middle East region with global industrial exports. Therefore, the availability of fully equipped ports in KSA with the capacity to effectively perform cargo handling activities and other related specialized functions is highly imperative, especially when it comes to international trade and shipping. Besides that, the port authority also plays a pivotal role in enhancing the country's economic activity through the import and export handling. In KSA, the Saudi Ports Authority (SPA) is responsible for nine main ports, namely (1) Jeddah Islamic Port, (2) King Abdulaziz Port Dammam, (3) King Fahad Industrial Port Yanbu, (4) King Fahad Industrial Port Jubail, (5) Jubail Commercial Port, (6) Yanbu Commercial Port, (7) Jizan Port, (8) Dhiba Port, and (9) Ras Al-Khair Port, with diverse specializations in the regional and international trades, which largely handle 95% of the country's imports and exports with 55% of the handled cargoes are exports (Elentably, 2015). Additionally, these ports handle more than five million twenty-foot equivalent units (TEUs) and cater to 11,000 ships annually (Elentably, 2015).
Despite the positive contribution to the GDP growth, the Saudi ports have encountered a critical problem-the overstock or accumulation of goods-due to the ineffective system in place, which contributes to the delay in moving goods and long waiting hours (Barky and Hussein, 2015), resulting in the increase of cargo handling cost (as much as 200%) (Arab, 2013). Such port crisis, undisputedly, has led to poor job performance and dissatisfaction among the cargo employees in SPA given the inadequate human resource practices (Arab News, 2013).
The concept of human resource, which emerged in the early 1980s, is typically assessed in terms of the relationship between human resource practices and job performance (Chand and Katou, 2007;Ramlall et al., 2012). The relationship between human resource practices and job performance is either direct (Arthur and Boyles, 2007;Huselid et al., 1997;Jackson and Schuler, 1995;Jouda et al., 2016) or indirect (Atteya, 2012;Belanger et al., 1999;Ferris et al., 2007). There are several studies that assessed the role of human resource practices in influencing job performance and satisfaction among employees (Jeet and Sayeeduzzafar, 2014), but similar studies within the context of Middle East region, specifically Saudi ports, are relatively scarce (Elentably, 2015). Hence, this study will evaluate the mediating effect of job satisfaction in the relationship between human resource practices and job performance among cargo employees in SPA.

Human Resource Practices
With the highly unstable global market with diverse challenges, most organizations demonstrate the propensity to focus on human resource practices to gain competitive advantage domestically and internationally (Atteya, 2012). Human resource practices are means across diverse fields that serve to enhance the employees' commitment, knowledge, and skills towards realizing organizational goals (Cania, 2014;Harter J. K. et al., 2002). Essentially, human resource practices encourage positive attitudes and behavior among employees in an organization as well as promoting a productive relationship between the employer and employees, which propel the employees' engagement in the creation and innovation (Tan and Nasurdin, 2006). The application of human resource practices supports the employees to gain higher job satisfaction and perform well even in the face of emerging challenges and dynamic nature of business. In other words, these practices present effective means for the organization to achieve success and realize the established organizational goals through employees (Armstrong, 2003).
The human resource management (HRM) was previously examined as a set of human resource practices in 104 studies (Boselie et al., 2005). There are various fundamental functions of an organization that are associated with the human resource practices, namely (1) training and development, (2) reward, (3) job analysis, (4) recruitment and selection, (5) employee relations, (6) employees' empowerment, and (7) social support (Delery and Doty, 1996;Nataraja and Alamri, 2016;Reid et al., 2002;Tsaur and Lin, 2002), which should be coherently integrated with distinct role descriptions to ensure high level of job performance and satisfaction among the employees in an organization (Albrecht et al., 2015;Dessler, 2007;Hassan, 2016;Jeet and Sayeeduzzafar, 2014;Majumder and Hossain, 2012). Although the HRM itself in the Middle East region demonstrates similar system to most developing countries, it is likely to be subjected to the influence of local cultural norms, which emphasizes the need to assess the human resource practices with specific reference to the KSA, especially among cargo employees in SPA (Alnaqbi, 2011).

Relationship Between Human Resource Practices and Job Performance
Notably, it is imperative to have the right individuals in the human resource to skillfully provide desirable environment for the employees to perform well through the different functions of an organization (Cania, 2014;Pfeffer and Villeneuve, 1994). Additionally, a manager or supervisor should emphasize the appropriate application of human resource practices to prevent any slip-ups (Guest, 2011; since how these practices are applied in an organization influence the performance of employees. After all, substantial empirical evidence on the positive relationship between human resource practices and job performance across diverse contexts were presented in prior studies (Arthur, 1994;Gerhart et al., 1992;Guest, 1997;Haddock-Millar et al., 2016;Huselid, 1995;Jouda et al., 2016;Mohinder, 2010;Shahzad et al., 2008;Tabiu and Nura, 2013;Vlachos, 2009);Gould-Williams (2003), which highlights the significance of human resource practices in enhancing job performance towards organizational goals (Hassan, 2016). Despite the numerous studies on the relationship between human resource practices and job performance within different contexts (Korde and Laghate, 2015;Shakeel and Lodhi, 2015), studies on human resource practices within the context of Middle East region are relatively scarce (Jouda et al., 2016), especially on the relationship between human resource practices and job performance among cargo employees in SPA.

Relationship Between Human Resource Practices and Job Satisfaction
Human resource practices are also means across diverse fields that offer job satisfaction among the employees (Bekru et al., 2017;Ting, 1997). Essentially, the human resource practices should be critically considered by the managers or supervisors as a method that improves the working environment for the employees and subsequently, increases the positive organizational outcomes (Absar et al., 2010). Additionally, there are strong evidence of a positive association between human resource practices and job satisfaction among employees in different organizational sectors, resulting in high job performance (Appelbaum et al., 2000;Atteya, 2012;Bartel, 1994;Becker and Gerhart, 1996). For instance, Gould-Williams (2003) assessed human resource practices in local government organizations in the United Kingdom, which revealed a positive relationship between human resource practices and job satisfaction, resulting in higher level of commitment, engagement, trust, and performance among the employees in realizing organizational goals. Additionally, there are substantial studies that provided empirical evidence on the positive relationship between human resource practices and job satisfaction across diverse fields as well as the significant influence of human resource practices towards engagement, loyalty, and even job performance among the employees (Al-Khasawneh, 2013;Balozi and Aman, 2014;Chaudhary and Bhaskar, 2016;Tabiu and Nura, 2013). However, the influence of human resource practices on job satisfaction among cargo employees in SPA receives little attention, which highlights the imperative need for this study to explore.

Relationship Between Job Satisfaction and Job Performance
Essentially, job satisfaction is related to the employees' positive emotional state towards their working environment (Smith et al., 1969) and job condition (Atteya, 2012;Brief and Weiss, 2002). Meanwhile, job performance is related to the employees' observable behavior when they perform their job with respect to the organizational goals (Campbell et al., 1990;Campbell et al., 1993). As the organization tends to focus on their employees' job performance in order to achieve the organizational goals (Hunter and Hunter, 1984), the -performance‖ should be viewed as the employees' behavior, not as the organizational outcomes. In other words, focusing on the organizational outcomes may directly propel the employees to attain the organizational goals in the shortest time, but such circumstance contributes to negative implications to the organization since the employees are not likely to exhibit desirable behavior in performing their job. Moreover, studies revealed that employees' attitude and emotional state towards their job and organization have significant effect on their job performance and organizational behavior (George, 2013;Harrison et al., 2006;Lawler and Porter, 1967;Ölçer, 2015;Schleicher et al., 2004;Wicker, 1969) .
The integral relationship between job satisfaction and job performance is the most venerable research aspect in the field of organizational psychology (Landy, 1989;Mitchell et al., 2017;Ölçer, 2015), which has propelled various studies to assess the relationship between job satisfaction and employees' performance across diverse sectors (Judge et al., 2001). Job satisfaction is an important factor that consistently contributes positive influence to the employees' performance (Feather and Kartin, 2004;Gosselin, 2005;Ölçer, 2015;Rae, 2013;Scingduenchai and Prasert, 2005;Yvonne et al., 2014). To date, a growing body of research across diverse fields concluded that the relationship between job satisfaction and job performance was positive (Arifin, 2015;Demirhan et al., 2014;H. et al., 2009;Harrison et al., 2006;Judge et al., 2001;Rusinah et al., 2016;Schleicher et al., 2004;Uzun and Özdem, 2017) as well as the positive influence of job satisfaction towards other related factors such as employees' engagement and loyalty towards the organization (Abraham, 2012;Davar and RanjuBala, 2012;Owusu, 2014;Ram, 2013;Waqas et al., 2014). However, similar studies within the context of Middle East region are relatively scarce, which propels this study to assess the influence of job satisfaction towards job performance among cargo employees in SPA.

Mediation Mechanism of Job Satisfaction
When the employees express dissatisfaction towards the application of human resource practices, such as reward, training and development, and recruitment and selection, their job performance is negatively affected. The human resource practices are viewed as an integral facet of job satisfaction that leads to positive job performance among employees (Koedel et al., 2017). Hence, how these human resource practices are introduced in an organization should be critically considered in order to satisfy the employees' needs and subsequently, motivate them to perform well. Job satisfaction was revealed to positively influence the employees' behavior, resulting in higher level of commitment, engagement, loyalty, and performance and lower occurrence of absenteeism, accident, tardiness, and turnover rate in an organization (Oshagbemi, 2003;Rothenberg et al., 2017;Rusinah et al., 2016). Additionally, job satisfaction, even as a mediating variable, was also found to positively influence job performance (Atteya, 2012;Khan et al., 2016;Uzun and Özdem, 2017). Substantial empirical evidence to support the positive relationship between human resource practices and job performance and other organizational outcomes through the mediation mechanism of job satisfaction within diverse contexts were revealed (Khan et al., 2016;Nabi et al., 2017). However, the lack of studies on the mediating role of job satisfaction in the relationship between human resource practices and job performance among cargo employees in SPA is deemed as a major literature gap, which will be addressed in this study.

Adams' Equity Theory
According to Adams' Equity Theory, the inputs and outputs should be fair ( Figure 1) to ensure high level of job satisfaction and performance among the employees in an organization. The implementation of equity or justice process within an organization may take several forms, such as interpersonal justice, informational justice, distributive justice, and procedural justice. Adding to that, the equity process should meet the perception of the employees-when the employees gain more than expected, they may feel guilty, but when the employees gain less than expected, they may feel displeased. Notably, the human resource practices in every organization should follow the procedural justice for high job satisfaction and performance (Deutsch, 1975;Mowday, 1991).

Figure-1. Adams' Equity Theory
Source: Safiullah (2015) The training and development, reward, recruitment and selection, job analysis, employee relations, employees' empowerment, and social support are identified as key factors that determine employees' job satisfaction and eventually, their job performance and productivity. These factors are viewed as independent variables that determine whether the employees are satisfied and deliver good performance at the workplace. Through Adams' Equity Theory, the job satisfaction of employees and its relation to the employees' job performance are rationalized (Montana and Charnov, 2014). Accordingly, Adams' Equity Theory postulated the need for equity between the employees' expectations (inputs) and what the employees gain in return (outputs) and the significance of the organization to strike a balance between inputs and outputs to realize maximum job performance among employees (Rothmann and Cooper, 2015). In other words, the inputs can be viewed as effort (to perform their job and improve their job performance) while the outputs (outcomes of performing their job) are deemed as reward.
This theory posited fair treatment for all employees with the emphasis of equivalent ratio of inputs and the corresponding outputs (Garavan et al., 2014). Furthermore, these inputs and outputs can only be assessed by comparing inputs and outputs of employees within the organization. Hence, an employee may express dissatisfaction when the employee notices other employee gains higher recognition and reward for the similar type of job. Consequently, the employee may not feel appreciated, resulting in poor job performance over time. However, if all employees are similarly rewarded, the employees collectively feel valued and eventually, perform well.
These inputs, which can be either assets or liabilities or grouped as relevant or irrelevant, are viewed as the contribution of employees to the relational exchange or in other words, the bargaining power of employees to the reward and cost. The relevant inputs include capital and manual labor, as these attributes legitimately entitle the employees to the reward. Meanwhile, irrelevant inputs are considered in the social setting, such as kindness and honesty. Therefore, employees' behavior that exhibits negativity, such as cruelty, is considered as a liability to the organization. The outcomes are perceived consequences that are earned from a relationship with another individual, such as salary, extension, praise, reputation, and recognition, which can be observed in the case of Saudi ports (Garavan et al., 2014).
There are various propositions under Adams' Equity Theory. Essentially, the main proposition of Adams' Equity Theory is the fair balance between inputs and outputs among employees to ensure maximum job performance. The organization must ensure that the employees who perform well are appropriately rewarded to sustain and eventually, increase their job performance Gould-Williams (2003). The employees continuously seek to maximize their outputs, which in this case, the outcome is deemed as reward without the inclusion of cost. The maximization of outputs can also be performed in a group through a system for apportionment of rewards and costs among the employees. Therefore, in a similar group, certain employees may receive punishment and the deserving employees are rewarded. Besides that, the theory also considers the proposition of distress-an inequitable relationship may result in distress. The employees in an inequitable relationship would continuously attempt to restore equity; thus, more people would be distressed with greater inequity and the attempt to restore equity among these people would intensify (Garavan et al., 2014).
Hence, it is imperative that the maximum impact of training and development as well as other organizational functions of human resource practices is delivered at the Saudi ports. Moreover, employees exhibit diverse behaviors, which should be comprehensively considered. Over the years, Saudi ports have demonstrated successful attempts in their training and development for the employees given their keen interest to satisfy the needs of their employees. With respect to this particular theory, employees who express job satisfaction are more likely to demonstrate enhanced job performance and productivity (Montana and Charnov, 2014) because their needs are considered by the organization, making them feel appreciated and acknowledged.
Essentially, the organization should provide high-quality training and development to equip the employees with the job skills (Ahmad and Schroeder, 2003), resulting in elevated satisfaction and performance at the workplace. Through training and development, the employees are able to acquire the necessary knowledge and enhance their capacity to sustain and improve their job performance (Atteya, 2012). Besides that, the equipment provided during these training and development courses should be adequate to ensure all employees have similar training opportunity  and to clear any doubts that the employees may have by exposing them to all key areas of the industry. The individual who is responsible for the training and development should be well-informed and possesses the expertise and capacity to address all questions posed by the employees . Furthermore, one should be able to perfectly explain the key concepts and trends of the industry to the employees in order to provide them satisfaction, which positively influences their performance (Lencioni, 2015). It is evident that a dissatisfied employee with low morale cannot deliver maximum job performance (Atteya, 2012 since the employee does not feel appreciated. Moreover, it becomes even more difficult for the employee to put in effort for the assigned duties when the organization does not offer reward to the employee. At this point, it is plausible that the employee expresses the intention of quitting, which may also influences other employees to follow suit. With that intention, the employee seeks a different career opportunity that offers job satisfaction (Montana and Charnov, 2014). Apart from training and development, this study also views reward as another independent variable that significantly influences the employees' job performance. Theoretically, the reward can be either intrinsic or extrinsic. In this case, the intrinsic reward is associated to the employee's personal satisfaction for performing a task Shin et al. (2015) whereas the extrinsic reward is tangibly provided by the organization to the employee for performing a task. Essentially, a reward program motivates employees to value the challenge of the assigned task and to complete the task well using the necessary skills and competencies (Abdul-Aziz et al., 2014). Such recognition from the organization also spurs the employees' desire to continuously self-improve and deliver improved job performance (Houseman, 2015). When the reward is appropriately provided, the employees are more likely to deliver the required level of job performance (Guest, 1997;Mohinder, 2010).
Meanwhile, job analysis is the preliminary hiring and recruitment process, which allows the organization to identify potential employees according to the details and requirements of the job. The job analysis helps the human resource manager to quantify the duties of the job and the appropriate salary for the hired employee. Through the job analysis, the organization knows what to expect from the employees and how to reward employees who demonstrate good performance; and in return, the employees know what the organization expects from them and the type of compensation and reward they receive (Garavan et al., 2014). According to Adams' Equity Theory, striking a fair balance is important to ensure good job performance among employees. The theory also explains the significance of considering the needs of the employees-the organization should keep their part of the bargain when the employees perform their responsibilities for the job to ensure a fair balance; otherwise, the employees may feel dissatisfied for being short-changed. The recruitment and selection process is another critical process that influences the employees' performance and productivity. Besides evaluating and determining the best fit for the particular job, this process also involves an in-depth discussion on the expectations of both organization and the potential employee (Atteya, 2012). This ensures that the hired employee for a particular position can meet the organization's expectations. Hence, the issue of equity is typically highlighted to ensure job satisfaction and job performance.
Good employee relations, as another identified factor that influences job performance, ensures that the organizational goals are achieved. Similarly, Adams' Equity Theory posited a fair balance between inputs and outputs for the employees, resulting in a satisfied workforce with enhanced job performance (Rothmann and Cooper, 2015). Adding to that, good social support, such as support groups and counseling programs (Abdul-Aziz et al., 2014), helps the employees to handle job-related challenges or stress effectively. This is another strategy of how an organization addresses the employees' needs. For instance, the organization should create an environment that is conducive for the employees to freely express themselves and discuss the challenges they encounter. Moreover, empowerment at the workplace also influences employees' job satisfaction and job performance. When the employees are empowered, their self-esteem increases and they are able to work with ease. Since fairness is advocated at the workplace with respect to Adams' Equity Theory, the employees' job satisfaction can be ensured (Tseng and Kuo, 2014).
Accordingly, the implementation of this theory in the United States, particularly Los Angeles, was explored, which revealed the significant role of recruitment and selection in the relationship between the employer and employees and in the development of an environment that is conducive to deliver the desired outcomes (Guerrero et al., 2014). Following that, this theory was also explored in the United Kingdom, which revealed that employees expect a fair return for their contribution to the organization and the determination of return among employees is typically based on social comparison; thus, employees who are in an inequitable circumstance may attempt to reduce the inequity through cognitive distortion, specifically distorting inputs or alternatively, leaving the organization (Houseman, 2015). Adding to that, Adams' Equity Theory, for the first time, was applied to explore the impact of deductible premium ratio towards customers' attitude on insurance frauds in Taiwan, which revealed evident relationship between deductible premium ratio and the perception of insurance frauds (Tseng and Kuo, 2014). Similar study was also conducted in the Major Gulf Corporation Council countries that encounter prolonged issue of workforce imbalance in order to develop support and developmental strategies to address this critical issue (Ryan, 2016). In another study by Shin et al. (2015), the influence of equity on executive employee pay disparity on job productivity and turnover across firms in North Korea was explored using the cross-country techniques, which clearly demonstrated that the employees' job performance was significantly affected by various job-related factors, including work input and motivation. Shin et al. (2015) also demonstrated that the inputs and outputs were directly affected when the first stage determinant model was applied and further proved the relevance and significant influence of executive multiple disclosures on the employees across various organizations. In view of the above, this study focuses on the cargo employees' job satisfaction through training and development, reward, recruitment and selection, job analysis, employee relations, employees' empowerment, and social support at Saudi ports, specifically SPA.

Maslow's Hierarchy of Needs
As shown in Figure 2, Maslow posited that there are five primary classes of human needs, which are to be hierarchically satisfied: (1) physiological needs; (2) safety and security; (3) belongingness; (4) self-esteem; (5) selfactualization (Akilu and Junaidu, 2015;Richter et al., 2015). Ideally, the needs of both personal and work life should be adequately fulfilled to gain a sense of contentment. For example, when the physiological needs (e.g., food, water, clothing, and shelter) at the most basic level in Maslow's Hierarchy of Needs are satisfied, one seeks to possess the next level of needs-security and safety-at home and at the workplace, and subsequently, to feel accepted and appreciated (the third level of needs) (Loeppke and Hohn, 2015). In the organizational context, employees are able to gain job satisfaction and eventually, perform well when the organization provides a working environment that is conducive to fulfil these fundamental needs. This theory highlighted various factors that motivate employees and how to structure their work accordingly (Singhapakdi et al., 2015). The organization that satisfies employees' needs for career development, job security, salary, and supervision is deemed to fulfill the first three basic needs of Maslow's Hierarchy of Needs (i.e., physiological needs, safety and security, and belongingness) . Most importantly, the organization should understand the individual and collective needs of employees in order to establish a working environment that is conducive.

Figure-2. Maslow's Hierarchy of Needs
Source: Maslow (1965) Accordingly, various organizational functions of human resource practices influence job satisfaction among employees. Firstly, training and development are viewed as effective organizational strategies that provide jobrelated skills and ensure job security among the employees at the workplace (Dhar, 2015). In other words, this function satisfies the employees' physiological needs, safety and security, and belongingness. Secondly, the reward in terms of salary, bonus, and any other form of monetary reward and compensation is considered as another strategy to provide job satisfaction to the employees. Essentially, appropriate reward management helps the employees to achieve their needs of different levels. The ability to achieve physiological needs provides financial comfort among the employees at the workplace (Malik et al., 2015) and subsequently, the sense of belongingness given the fulfillment of their prior needs through reward (Dwarakish and Salim, 2015). Thirdly, fair recruitment and selection assure employees in attaining and maintaining their job, which satisfy their physiological needs, as well. As their physiological needs are satisfied, the assurance provided for their job security and financial security fulfills the employees' needs in the second level of Maslow's hierarchy of needs (Ufoma et al., 2015). With the fulfillment of the first two levels of Maslow's hierarchy of needs, the employees are able to satisfy the subsequent level of needs (belongingness). On a similar note, fair job analysis, good employee relations, and employees' empowerment are also deemed to contribute to the fulfillment of employees' physiological needs, safety and security, and belongingness since these functions provide the employees the opportunity to nurture a solid relationship among one another and to strengthen their connection with the organization (Rubin and Babbie, 2016). Additionally, it is also imperative that the organization provides adequate social support to demonstrate appreciation and concern for the employees (Shabbir et al., 2018). For examples, housing support, meals, medical and insurance cover, and maternity and paternity leave (Jain, 2015). The social support in the forms of housing and meals satisfies the employees' physiological needs (Jain, 2015). Meanwhile, the medical and insurance cover satisfies the employees' second level of needs (safety and security) in the case of any illness or mishaps at the workplace (Loeppke and Hohn, 2015). As for the social support in the form of maternity and paternity leave, the employees are assured to realize their subsequent level of needs that involves their family and friends (Sonnentag and C., 2015). Consequently, job satisfaction spurs the employees' drive to deliver expected organizational outcomes through enhanced job performance (Gubler et al., 2016). Employees who express job satisfaction tend to demonstrate loyalty, commitment (Jain, 2015), and motivation (Lăzăroiu, 2015), higher job performance and efficiency, and increased productivity (Jain, 2015;Jaiswal and Dhar, 2016;Lăzăroiu, 2015;Timms et al., 2015) with minimal supervision required .

Conceptual Framework
This study will evaluate the relationship between human resource practices and job performance among cargo employees in SPA with their job satisfaction as the mediating variable. Based on the empirical evidence on the influence of human resource practices on employees' job performance (Nassazi, 2013), the notion of job satisfaction among employees is indeed in line with Maslow's Hierarchy of Needs-that employees express satisfaction when their needs are satisfied by the organization (Maslow, 1965). For instance, Balozi and Aman (2014) and Manzoor et al. (2015) empirically demonstrated that the relationship between human resource practices and job satisfaction is positive while Snell et al. (2013) revealed significant relationship between human resource practices and job performance through job satisfaction. Following the conceptualization of Maslow's Hierarchy of Needs (Figure 3), this study proposes the following hypotheses for testing: H 1 : There is a positive relationship between human resource practices and job performance among cargo employees in SPA.
H 2 : There is a positive relationship between human resource practices and job satisfaction among cargo employees in SPA.
H 3 : There is a positive relationship between job satisfaction and job performance among cargo employees in SPA.
H 4 : Job satisfaction mediates the relationship between human resource practices and job performance among cargo employees in SPA.

Research Design
In general, a research design is explained in terms of the means or strategies used in conducting a study. According to Creswell (2012), there are three phases in a research design, namely theoretical perspectives, procedures involved, and data collection and analysis. Accordingly, this study will adopt a quantitative research design for the testing of proposed hypotheses on the influence of human resource practices and job satisfaction on the job performance. Through a quantitative research design, specifically the questionnaire survey approach, this study will employ reductionistic approach to test different sets of testable variables with respect to the proposed research questions and hypotheses.
The questionnaire survey approach is regarded as an effective and straightforward research tool Zikmund W. (2003) without the influence of -interview bias‖. Additionally, the anonymous nature of the questionnaire survey approach allows the respondents to freely express their personal values and views (Alnaqbi, 2011). It is also regarded as one of the simple strategies to collect a substantial amount of data from the targeted population within a limited timeframe (Haque and Taher, 2008;Levin, 2006;Yu and Egri, 2005). With that, this study is able to assess the underlying relationships between these variables to grasp the phenomenon of interest (Asad et al., 2018a) (Tseng and Kuo, 2014) (Tseng and Kuo, 2014) (Tseng and Kuo, 2014) . Another key aspect of a research design is the unit of analysis (Walliman, 2017;Zikmund W. G. et al., 1997). In this study, the cargo employees in SPA represent the unit of analysis. The cross-sectional study design, which refers to the process of conducting data collection at a single point of time, will be used as a strategic process to obtain the required data from the population of interest in this study.

Data collection 5.2.1. Population and Sample Size
This study focused on cargo employees in SPA under the Saudi Government (public). There are nine main ports in KSA, namely (1) Jeddah Islamic Port, (2) King Abdulaziz Port Dammam, (3) King Fahad Industrial Port Yanbu, (4) King Fahad Industrial Port Jubail, (5) Jubail Commercial Port, (6) Yanbu Commercial Port, (7) Jizan Port, (8) Dhiba Port, and (9) Ras Al-Khair Port, which serve as the targeted population of this study. This study will select an appropriate sample size from the population of interest.
Essentially, it is imperative to gather an adequate sample size that statistically represents the population of interest in an empirical study for generalization of findings. The determination of sample size depends on the population, of either unknown (infinite) population or known (finite) population. It was reported that there are about 8,000 cargo employees in Saudi ports (Saudi Ports Authority, 2017) hence, this study determines the selection of sample size based on a finite population (Best and Kahn, 2016;Krejcie and Morgan, 1970;Solomon, 2017). Hence, according to Krejcie and Morgan (1970), a sample size of 367 is selected for this study.

Sampling Strategy
There are probability and non-probability sampling strategies (Saunders et al., 2007;Sekaran, 2007). The latter will be employed in this study due to an unknown sampling frame of these Saudi Ports, specifically the number of cargo employees in SPA. There are various non-probability sampling strategies, namely (1) convenience sampling strategy, (2) quota sampling strategy, (3) judgmental sampling strategy, (4) snowball sampling strategy, and (5) selfselection sampling strategy (Brannen, 2017;Cavana et al., 2001). Hence, this study considers the convenience sampling strategy given the simplicity of its process using limited resources. In other words, only cargo employees who are available and willing to participate in the questionnaire survey will be considered.

Instrument
Studies by Cook et al. (1981), Harter S. (1985), Snell and Dean (1992), Boselie et al. (2001), Laka-Mathebula (2004), Singh (2004), Morgeson and Humphrey (2006) and Qureshi et al. (2007) are used as the primary sources in the development of instrument for this study. This study will adopt and adapt the constructs and items accordingly. The questionnaire survey approach using the five-point Likert scale with endpoints of -strongly disagree‖ (1) and -strongly agree‖ (5) will be employed for this study based on several rationalizations. There are various scales of measurement from three-point Likert scale up to a Likert scale of more than 10 points (Geuens and De, 2017). The Likert scale, which is a single rating approach (Davidson, 1979) or one of the most familiar scale of measurements, is widely used in quantitative research that measures multiple variables in a relationship. This study considers the preferred five-point Likert scale (Revilla et al., 2014) given its appropriateness in obtaining the respondents' responses (of agree and disagreement) (Cox, 1980;Revilla et al., 2014).
Considering that the first language of the targeted population is Arabic language, this study will develop the instrument in Arabic language using the back-translation method. The instrument will be translated from English language to Arabic language and back translated to English language for accuracy. The developed instrument with tested reliability and validity will be used for this study. The randomly selected respondents are then required to complete the questionnaire survey that comprises several sections on human resource practices, job satisfaction, and job performance (Asad et al., 2018b). The instrument will also include a section to acquire demographic information of the respondents to understand the overall sample.

Data Analysis
Following the data collection, this study will perform data screening and cleaning to identify any missing data and potential outliers as well as preliminary analysis (including descriptive analysis, such as mean scores and standard deviations) to assess data normality, reliability (based on the Cronbach's alpha coefficients), and validity using IBM SPSS (version 22). Besides that, the obtained data will be analyzed using the descriptive-inferential method.
There are seven independent variables that reflect human resource practices in this study, namely (1) training and development, (2) reward, (3) job analysis, (4) recruitment and selection, (5) social support, (6) employee relations, and (7) employees' empowerment. Meanwhile, job satisfaction is assessed as a mediating variable in the relationship between human resource practices and job performance whereas job performance is the dependent variable in this study.
Adopting the method of Baron and Kenny (1986), this study will conduct the mediation test with structural equation modelling (SEM). Their method will be applied in this study as the underlying basis to establish the mediating role of job satisfaction in the relationship between human resource practices and job performance. In order to prove the mediating effect of job satisfaction, this study will ensure that the following requirements are met: (1) the independent variable (human resource practices) significantly affects the dependent variable (job performance); (2) the independent variable (human resource practices) significantly affects the mediating variable (job satisfaction); (3) the mediating variable (job satisfaction) significantly affects the dependent variable (job performance); (4) the effects of independent variable (human resource practices) on the dependent variable (job performance) are meaningless (full medium) or decreases (partial medium)-which in this case, the effects of both independent and mediating variables are to be calculated.

Conclusion
The Saudi ports have immense economic contributions to the Kingdom of Saudi Arabia given its diverse economic activities. However, the critical problem of overstock or accumulation of goods at Saudi ports, which may be contributed by inadequate human resource practices (Arab News, 2013), has greatly affected the cargo employees, resulting in low job satisfaction and performance. Evidently, the human resource practices serve an imperative role for the organizations to gain competitive advantages in competing at the global stage. Moreover, empirical evidence on the positive contributions of human resource practices towards the employees' satisfaction and performance are substantial (Aktar and Pangil, 2017;Bustamam et al., 2014;Nwachukwu and ChladkovÃ¡, 2017;Sutanto and Kurniawan, 2016). It is significant that the needs of employees are adequately satisfied to ensure their job satisfaction, resulting in enhanced job performance (Kuppuswamy et al., 2017). The relationships of human resources practices, job satisfaction, and job performance within the context of Middle East region are inadequately explored. Hence, this study will evaluate the mediating effect of job satisfaction in the relationship between human resource practices and job performance among cargo employees in Saudi ports with respect to Adams' Equity Theory and Maslow's Hierarchy of Needs. Specifically, this study serves to provide empirical evidence on (1) the relationship between human resource practices and job performance, (2) the relationship between human resource practices and job satisfaction, (3) the relationship between human resource practices and job performance, and (4) the mediating effect of job satisfaction in the relationship between human resource practices and job performance.